Date   
Re: KF4ZTI 11 latex floater now over Tulsa OK

Zack Clobes W0ZC
 

The floater seems to be descending slowly.

As for the visual, yes they look like a star in the day fly. They're really cool to watch and especially when they pop.

Zack


On Sun, Jun 14, 2020, 9:38 AM James Ewen VE6SRV <ve6srv@...> wrote:
Harry might be wearing glasses if he has bad vision. Most likely just using his eyes. 

A 1200 gram balloon at that altitude is easy to spot. It will be a little white dot in the sky. 

The balloon will be about 30 feet or so across. 

It is kind of hard to imagine being able to see a balloon so far away until you actually see one. I recall seeing my first HAB at altitude and being amazed that I could see it. 

One flight we did, we put a very light payload in a 1 cu ft styrofoam box with no parachute. Just a tumble recovery.  

I was watching the flight with binoculars when the balloon burst. I was able to watch the box fall to the earth. 

I watched it down to about 30,000 feet where I foolishly thought “I’ll have a look for be box with my naked eyes!”. I was unable to find the box with the binoculars after that. 

Recovered the payload a couple miles from where we were watching the burst. 

James
VE6SRV


On Sun, Jun 14, 2020 at 8:31 AM Hank Riley via groups.io <n1ltv=yahoo.com@groups.io> wrote:
Bill,

What kind of optical aid is Harry using?  Very appropriate he of all people is getting that treat.

Hank
_______________________


On Sunday, June 14, 2020, 10:24:04 AM EDT, Bill wrote:

Harry KC5TRB has a visual sighting of the KF4ZTI-11 latex floater as it flies nearly over the top of his house in Tulsa OK at 108,000 feet. It has been flying now for 25 hours.

--
James
VE6SRV

Re: KF4ZTI 11 latex floater now over Tulsa OK

James Ewen VE6SRV
 

Harry might be wearing glasses if he has bad vision. Most likely just using his eyes. 

A 1200 gram balloon at that altitude is easy to spot. It will be a little white dot in the sky. 

The balloon will be about 30 feet or so across. 

It is kind of hard to imagine being able to see a balloon so far away until you actually see one. I recall seeing my first HAB at altitude and being amazed that I could see it. 

One flight we did, we put a very light payload in a 1 cu ft styrofoam box with no parachute. Just a tumble recovery.  

I was watching the flight with binoculars when the balloon burst. I was able to watch the box fall to the earth. 

I watched it down to about 30,000 feet where I foolishly thought “I’ll have a look for be box with my naked eyes!”. I was unable to find the box with the binoculars after that. 

Recovered the payload a couple miles from where we were watching the burst. 

James
VE6SRV


On Sun, Jun 14, 2020 at 8:31 AM Hank Riley via groups.io <n1ltv=yahoo.com@groups.io> wrote:
Bill,

What kind of optical aid is Harry using?  Very appropriate he of all people is getting that treat.

Hank
_______________________


On Sunday, June 14, 2020, 10:24:04 AM EDT, Bill wrote:

Harry KC5TRB has a visual sighting of the KF4ZTI-11 latex floater as it flies nearly over the top of his house in Tulsa OK at 108,000 feet. It has been flying now for 25 hours.

--
James
VE6SRV

Re: KF4ZTI 11 latex floater now over Tulsa OK

Hank Riley
 

Please, now that the situation has settled down a little, tell us a little more about the hardware.  Who designed it and built it?  Microcontroller employed?

What should have been the lift?
____________________________________________________________________________

 This is an unplanned latex floater due to KF4ZTI putting in only a few ounces of positive lift on a 1200 gram balloon.

Re: KF4ZTI 11 latex floater now over Tulsa OK

Hank Riley
 

Bill,

What kind of optical aid is Harry using?  Very appropriate he of all people is getting that treat.

Hank
_______________________


On Sunday, June 14, 2020, 10:24:04 AM EDT, Bill wrote:

Harry KC5TRB has a visual sighting of the KF4ZTI-11 latex floater as it flies nearly over the top of his house in Tulsa OK at 108,000 feet. It has been flying now for 25 hours.

Re: KF4ZTI 11 latex floater now over Tulsa OK

Bill Brown
 

Harry KC5TRB has a visual sighting of the KF4ZTI-11 latex floater as it flies nearly over the top of his house in Tulsa OK at 108,000 feet. It has been flying now for 25 hours.

1200 gram latex balloon (hydrogen) with a one pound payload and about 2 ounces of free lift.

- Bill WB8ELK


-----Original Message-----
From: Bill Brown via groups.io <wb8elk@...>
To: GPSL@groups.io <GPSL@groups.io>
Sent: Sun, Jun 14, 2020 9:19 am
Subject: Re: [GPSL] KF4ZTI 11 latex floater now over Tulsa OK

Update on the KF4ZTI-11 latex floater. Thanks to Harry KC5TRB in Tulsa OK for dusting off his APRS setup and establishing an iGate tuned to the higher frequency. It is now directly over his house in Tulsa OK having floating all night bouncing between 92,000 and 95,000 feet and is now back at 108,000 feet now that the Sun is heating it up again. The battery pack went out an hour before sunrise but came back now that the bubble-wrap insulation is allowing the payload to reach temperatures over 20 degrees C. It was -45 deg C most of the night. (Eveready AAA lithiums 4-pack). Now that the internal temp is over 20 C, the frequency has drifted back to around 144.342 and 144.392 MHz so should work with digipeaters and iGates again.

Should be heard from Omaha to Houston now and all over OK, AR, KS and MO.

Now it is just a matter of time to see how long it can survive the UV radiation.

- Bill WB8ELK


-----Original Message-----
From: Bill Brown via groups.io <wb8elk@...>
To: GPSL@groups.io <GPSL@groups.io>
Sent: Sat, Jun 13, 2020 10:45 pm
Subject: Re: [GPSL] KF4ZTI11 latex floater heading across Arkansas tonight

Update on the KF4ZTI-11 latex floater. After sunset it dropped from 108000 feet (where it spent most of the day) down to 92000 feet where it has leveled off. APRS frequencies now have settled down to 144.351 MHz and 144.401 MHz. I'm still decoding it on 144.351 MHz from 255 miles away as it travels west across Arkansas tonight. Harry KC5TRB is hearing it now in Tulsa and getting partial decodes on APRS.  Mike W0MB in Kansas City can hear it weakly but doesn't have a way to decode the APRS packets. At the current rate of speed and westerly heading it will likely be in Oklahoma by sunrise tomorrow.

- Bill WB8ELK


-----Original Message-----
From: Bill Brown via groups.io <wb8elk@...>
To: gpsl@groups.io <gpsl@groups.io>
Sent: Sat, Jun 13, 2020 9:23 pm
Subject: [GPSL] KF4ZTI11 latex floater heading across Arkansas tonight

KF4ZTI-11 was launched this morning (Saturday) from Clarksville TN with just one pound of payload attached. GoPro type camera and an APRS tracker. It transmits every 1 minute on 144.39 and then 10 seconds later on 144.34 MHz...This payload sat in a tree for a week or two last year and saw quite a bit of weather. As a result the transmit frequency has shifted to 144.348 MHz on APRS as well as 144.398 MHz when it gets below -20 C...As a result it is out of the passband for most digipeaters. I am still copying it here in Huntsville AL from 220 miles out but is about out of range for me. Is there someone in the St. Louis, Kansas City, Little Rock, Memphis or east OK or NE TX that can set up an iGate tuned to 144.348 MHz tonight? If you already have an iGate, can you tune it to 144.398 or 144.348 MHz? This is an unplanned latex floater due to KF4ZTI putting in only a few ounces of positive lift on a 1200 gram balloon. It floated all day around 107000 feet but is descending after sunset...probably will level out around 90,000 feet and continue on west across Arkansas tonight.

- Bill WB8ELK


Re: KF4ZTI 11 latex floater now over Tulsa OK

Bill Brown
 

Update on the KF4ZTI-11 latex floater. Thanks to Harry KC5TRB in Tulsa OK for dusting off his APRS setup and establishing an iGate tuned to the higher frequency. It is now directly over his house in Tulsa OK having floating all night bouncing between 92,000 and 95,000 feet and is now back at 108,000 feet now that the Sun is heating it up again. The battery pack went out an hour before sunrise but came back now that the bubble-wrap insulation is allowing the payload to reach temperatures over 20 degrees C. It was -45 deg C most of the night. (Eveready AAA lithiums 4-pack). Now that the internal temp is over 20 C, the frequency has drifted back to around 144.342 and 144.392 MHz so should work with digipeaters and iGates again.

Should be heard from Omaha to Houston now and all over OK, AR, KS and MO.

Now it is just a matter of time to see how long it can survive the UV radiation.

- Bill WB8ELK


-----Original Message-----
From: Bill Brown via groups.io <wb8elk@...>
To: GPSL@groups.io <GPSL@groups.io>
Sent: Sat, Jun 13, 2020 10:45 pm
Subject: Re: [GPSL] KF4ZTI11 latex floater heading across Arkansas tonight

Update on the KF4ZTI-11 latex floater. After sunset it dropped from 108000 feet (where it spent most of the day) down to 92000 feet where it has leveled off. APRS frequencies now have settled down to 144.351 MHz and 144.401 MHz. I'm still decoding it on 144.351 MHz from 255 miles away as it travels west across Arkansas tonight. Harry KC5TRB is hearing it now in Tulsa and getting partial decodes on APRS.  Mike W0MB in Kansas City can hear it weakly but doesn't have a way to decode the APRS packets. At the current rate of speed and westerly heading it will likely be in Oklahoma by sunrise tomorrow.

- Bill WB8ELK


-----Original Message-----
From: Bill Brown via groups.io <wb8elk@...>
To: gpsl@groups.io <gpsl@groups.io>
Sent: Sat, Jun 13, 2020 9:23 pm
Subject: [GPSL] KF4ZTI11 latex floater heading across Arkansas tonight

KF4ZTI-11 was launched this morning (Saturday) from Clarksville TN with just one pound of payload attached. GoPro type camera and an APRS tracker. It transmits every 1 minute on 144.39 and then 10 seconds later on 144.34 MHz...This payload sat in a tree for a week or two last year and saw quite a bit of weather. As a result the transmit frequency has shifted to 144.348 MHz on APRS as well as 144.398 MHz when it gets below -20 C...As a result it is out of the passband for most digipeaters. I am still copying it here in Huntsville AL from 220 miles out but is about out of range for me. Is there someone in the St. Louis, Kansas City, Little Rock, Memphis or east OK or NE TX that can set up an iGate tuned to 144.348 MHz tonight? If you already have an iGate, can you tune it to 144.398 or 144.348 MHz? This is an unplanned latex floater due to KF4ZTI putting in only a few ounces of positive lift on a 1200 gram balloon. It floated all day around 107000 feet but is descending after sunset...probably will level out around 90,000 feet and continue on west across Arkansas tonight.

- Bill WB8ELK


Re: KF4ZTI11 latex floater heading across Arkansas tonight

Bill Brown
 

Update on the KF4ZTI-11 latex floater. After sunset it dropped from 108000 feet (where it spent most of the day) down to 92000 feet where it has leveled off. APRS frequencies now have settled down to 144.351 MHz and 144.401 MHz. I'm still decoding it on 144.351 MHz from 255 miles away as it travels west across Arkansas tonight. Harry KC5TRB is hearing it now in Tulsa and getting partial decodes on APRS.  Mike W0MB in Kansas City can hear it weakly but doesn't have a way to decode the APRS packets. At the current rate of speed and westerly heading it will likely be in Oklahoma by sunrise tomorrow.

- Bill WB8ELK


-----Original Message-----
From: Bill Brown via groups.io <wb8elk@...>
To: gpsl@groups.io <gpsl@groups.io>
Sent: Sat, Jun 13, 2020 9:23 pm
Subject: [GPSL] KF4ZTI11 latex floater heading across Arkansas tonight

KF4ZTI-11 was launched this morning (Saturday) from Clarksville TN with just one pound of payload attached. GoPro type camera and an APRS tracker. It transmits every 1 minute on 144.39 and then 10 seconds later on 144.34 MHz...This payload sat in a tree for a week or two last year and saw quite a bit of weather. As a result the transmit frequency has shifted to 144.348 MHz on APRS as well as 144.398 MHz when it gets below -20 C...As a result it is out of the passband for most digipeaters. I am still copying it here in Huntsville AL from 220 miles out but is about out of range for me. Is there someone in the St. Louis, Kansas City, Little Rock, Memphis or east OK or NE TX that can set up an iGate tuned to 144.348 MHz tonight? If you already have an iGate, can you tune it to 144.398 or 144.348 MHz? This is an unplanned latex floater due to KF4ZTI putting in only a few ounces of positive lift on a 1200 gram balloon. It floated all day around 107000 feet but is descending after sunset...probably will level out around 90,000 feet and continue on west across Arkansas tonight.

- Bill WB8ELK


Re: KF4ZTI11 latex floater heading across Arkansas tonight

Mike Bogard
 

I am hearing the 144.351 but not the frequency. Very light copy on the kf4zti-11 balloon payload. I don't have anyway to decode right now so sorry about that. Mike w0mb in Kansas City Mo home of the Chiefs

On 6/13/2020 9:23 PM, Bill Brown via groups.io wrote:
KF4ZTI-11 was launched this morning (Saturday) from Clarksville TN with just one pound of payload attached. GoPro type camera and an APRS tracker. It transmits every 1 minute on 144.39 and then 10 seconds later on 144.34 MHz...This payload sat in a tree for a week or two last year and saw quite a bit of weather. As a result the transmit frequency has shifted to 144.348 MHz on APRS as well as 144.398 MHz when it gets below -20 C...As a result it is out of the passband for most digipeaters. I am still copying it here in Huntsville AL from 220 miles out but is about out of range for me. Is there someone in the St. Louis, Kansas City, Little Rock, Memphis or east OK or NE TX that can set up an iGate tuned to 144.348 MHz tonight? If you already have an iGate, can you tune it to 144.398 or 144.348 MHz? This is an unplanned latex floater due to KF4ZTI putting in only a few ounces of positive lift on a 1200 gram balloon. It floated all day around 107000 feet but is descending after sunset...probably will level out around 90,000 feet and continue on west across Arkansas tonight.

- Bill WB8ELK


KF4ZTI11 latex floater heading across Arkansas tonight

Bill Brown
 

KF4ZTI-11 was launched this morning (Saturday) from Clarksville TN with just one pound of payload attached. GoPro type camera and an APRS tracker. It transmits every 1 minute on 144.39 and then 10 seconds later on 144.34 MHz...This payload sat in a tree for a week or two last year and saw quite a bit of weather. As a result the transmit frequency has shifted to 144.348 MHz on APRS as well as 144.398 MHz when it gets below -20 C...As a result it is out of the passband for most digipeaters. I am still copying it here in Huntsville AL from 220 miles out but is about out of range for me. Is there someone in the St. Louis, Kansas City, Little Rock, Memphis or east OK or NE TX that can set up an iGate tuned to 144.348 MHz tonight? If you already have an iGate, can you tune it to 144.398 or 144.348 MHz? This is an unplanned latex floater due to KF4ZTI putting in only a few ounces of positive lift on a 1200 gram balloon. It floated all day around 107000 feet but is descending after sunset...probably will level out around 90,000 feet and continue on west across Arkansas tonight.

- Bill WB8ELK


Re: Saturday flight

Mark Conner N9XTN
 

Thanks John.  I'll try RAW again on my next flight with the Canon point and shoot.  Lightroom is probably too big a leap in cost for me - do you have another software package to recommend?  The extent of my photo editing experience has been Paint Shop Pro and Google's Picasa.

- Mark

On Wed, Jun 10, 2020 at 10:57 PM John Kovac KM6GKF <jkovac@...> wrote:
T4i would be awesome.  

I’m shooting in RAW format, so not editing the photos is not an option, plus the files are huge, but it’s worth it in my opinion.  Not doing much with color, but the Dehaze filter in Adobe Lightroom is amazing.  It brings out detail really well. Also making heavy use of the Texture filter.  On some of the images between the clouds I also used a Linear Gradient, which allows you to edit the parts of a horizon-split shot separately.

Lightroom CC is a significant monthly fee, and the support sucks, but it’s still the best choice for my needs.  Works well with RAW, intuitive controls, really powerful. 



On Jun 10, 2020, at 8:22 PM, Mark Conner N9XTN <mconner1@...> wrote:


Did you do a lot of color work to bring the detail out and cut the haze?  I've been using Canon point-and-shoot cameras with CHDK firmware and I get a lot of haze in many of my shots.  I have not invested much time or money in photo editing software, which I may need to do.  Part of the issue is flying in Great Plains summers when there is a boatload of moisture in the air - you guys probably have drier atmospheres most of the time.

I have a T4i that is several years old and have been thinking of getting a newer model, so a balloon cam might be a good use for the old one.

73 de Mark N9XTN


On Wed, Jun 10, 2020 at 8:35 PM John Kovac KM6GKF <jkovac@...> wrote:
Thanks Mark.

Setup up is cheap DSLR, Canon Rebel T7.  I was using a T2i that I bought for $100 on eBay but out last payload was stolen.  So I splurged and bought a new T7 (not T7i which has multiple advantages but costs way more.). It was $400 for a kit with a 50mm lens.  For the lens here I used Canon 10-18mm zoom, under $300 new.  The zoom is obviously useless for this application but as far as I know, there is no prime lens that wide for that cheap that fits a Canon EF mount.   Using a $20 intervalometer to trigger the shutter every 10 seconds.  I know there is program called Magic Lantern that people use instead of an intervalometer but the intervalometer is cheap, lightweight, and really easy to use.



On Jun 10, 2020, at 6:13 PM, Mark Conner N9XTN <mconner1@...> wrote:


Great photos, John!  Makes me think about wanting to risk a DSLR on a future flight.  What's your DSLR setup (camera and lens)?

73 de Mark N9XTN

On Wed, Jun 10, 2020 at 7:45 PM John Kovac KM6GKF <jkovac@...> wrote:
Hi all,

First, thanks again to everyone on this list for the amazing support on our previous flight.

This time, the payload was not stolen.

It was a very long flight because the balloon hung out for a long time at high altitude, thought maybe we had a slow leak that was gonna send us over the ocean.  Still not sure what happened there, but it did finally break just short of 114,000 feet. The DSLR died at about 4 and a half hours, but the GoPro3+ on a Sabient add-on battery pack ran for almost six hours, and got the landing on video for the first time ever for us.

Flickr (stills) and YouTube (video) links below.

Best,

John Kovac










Re: Additional talks sought for GPSL 2020

Mark Conner N9XTN
 

A big thank you to those who have contacted me to volunteer to present at GPSL.  We have about 10 right now, including one from the UK and one from India.  I am going to compile a list later this weekend and will share with the group to make sure I didn't overlook someone who contacted me.  I have been somewhat distracted lately with setting up my company's branch office and getting it prepared for (re-)opening.  

I am still taking names/topics but we'll soon approach a full slate.  If you'd like to give a talk, contact me soon to ensure a spot in the agenda.

73 de Mark N9XTN

On Fri, Jun 12, 2020 at 9:31 PM Mark Conner N9XTN via groups.io <mconner1=gmail.com@groups.io> wrote:
GPSLers,

We still have room for additional talks for the Friday session!  I'd like to extend a particular invitation to those outside the US who might want to present something.  I know our UK friends in particular have had to be very creative with their RF solutions given their strict regulatory environment, and I'm sure many of us who are the "usual" GPSL attendees would like to hear how they overcame those limits (and stretched the state of the art in doing so).  I'm sure there are plenty of similar stories from elsewhere.

This is a great opportunity to see what other ARHAB communities are doing and cross-feed some ideas from around the world.

Our session will run from roughly 1400-2200 UTC on July 10 (exact timing will depend on number/duration of talks).  Please contact me at n9xtn@... if you are interested in presenting.  This is a collegial environment and don't be concerned if you're not a PowerPoint wizard or a Dale Carnegie speaker.  

73 de Mark N9XTN

Re: Imaging the Surface

L. Paul Verhage KD4STH
 

Whoa, that's better than I was getting. I'm about 6 degrees further north than San Francisco, so I may need a slightly larger antenna.

$200 for a GOES station is about what I paid for a APT black and white station. Back then, the receiver was a cheap short wave receiver with its IF filter removed so it could handle the Doppler shift. 

Let me start collecting some pennies.

On Sat, Jun 13, 2020, 9:44 AM James Hannon <jmhannon@...> wrote:
Paul Try this.

https://pietern.github.io/goestools/guides/minimal_receiver.html

Jim H

On 6/13/2020 10:27 AM, L. Paul Verhage KD4STH wrote:
> A ling time ago I use to receive APT images from some NOAA weather
> satellites. Those were black and white raster images that built up line
> by line.
>
> Some time I'll need to find out if I can do that again. It was a fun
> project back in 1992 and 1993.
>
> If I remember correctly, I got images from NOAA-9 through 12.
>

--
WB0TXL
WEB Page http://www.ocrslc.net/
Blog http://jimhannon.wordpress.com
CoCoRaHS station IA-LN-7
42,11.90N,91,39.26W





Re: Imaging the Surface

James Hannon
 

On 6/13/2020 10:27 AM, L. Paul Verhage KD4STH wrote:
A ling time ago I use to receive APT images from some NOAA weather satellites. Those were black and white raster images that built up line by line.
Some time I'll need to find out if I can do that again. It was a fun project back in 1992 and 1993.
If I remember correctly, I got images from NOAA-9 through 12.
--
WB0TXL
WEB Page http://www.ocrslc.net/
Blog http://jimhannon.wordpress.com
CoCoRaHS station IA-LN-7
42,11.90N,91,39.26W

Re: Imaging the Surface

L. Paul Verhage KD4STH
 

A ling time ago I use to receive APT images from some NOAA weather satellites. Those were black and white raster images that built up line by line. 

Some time I'll need to find out if I can do that again. It was a fun project back in 1992 and 1993.

If I remember correctly, I got images from NOAA-9 through 12.

On Sat, Jun 13, 2020, 9:04 AM Creager, Gerald J - Capt, CAP - Health Services Officer - (SWR-OK-001) <gerald.j.creager@...> wrote:
The big satellites use sensors on a bunch of discrete wavelengths, and the bandwidth of the sensors isn't too broad. They bring all the wavelengths down and post-process them into false-color images for almost everything released to the public, but there are some sensors that are "true color". These require significant pixel counts, but again, the image mechanism is different: Most are still line-scanners. Very fast line scanners. This allows them to keep the focus and parallax in control, and, their imagery is attitude stabilized, so they are always looking at the same angle, depending on mission.

Weather satellites are like this, although they might be looking with 20 different instruments at the same scene. The bandwidth is significant.

73
Gerry N5JXS



CAP E-Mail Logo

Capt Gerald J Creager, CAP
Health Services Officer - (SWR-OK-001)
(H) 979.229.5301
(C) 979.229.5301
U.S. Air Force Auxiliary
https://www.GoCivilAirPatrol.com/
https://www.okwgcap.org/
https://www.okwgcap.org/wingstaff




From: GPSL@groups.io <GPSL@groups.io> on behalf of Joe WB9SBD via groups.io <nss=mwt.net@groups.io>
Sent: Thursday, June 11, 2020 21:42
To: GPSL@groups.io <GPSL@groups.io>
Subject: Re: [GPSL] Imaging the Surface
 
Thats what I was wondering how the Government from orbit has perfectly neutral colors.

Joe WB9SBD

On 6/11/2020 6:25 PM, L. Paul Verhage KD4STH wrote:
Yeah, I always see blue unless I shoot black and white near infrared.

On Thu, Jun 11, 2020, 5:02 PM Joe WB9SBD <nss@...> wrote:
I have yet to see a pic from say 60K and up from anyone's balloon, that you can say the image of the ground even when looking straight down is not color shifted way into the blue.

it's almost like a Black and white TV picture except it's Blue and white, everything is various shades of Blue.

Joe WB9SBD

On 6/11/2020 5:37 PM, L. Paul Verhage KD4STH wrote:
Interesting. I know near infrared penetrates the air like it wasn't there. But shorter wavelength light like blue is strongly scattered.

Perhaps because the satellite looks straight down, there's less air to scatter the light. When we look horizontally through the air, we are looking through miles of air at roughly the same density. When you look down, you are seeing throgh a column of air that increases the closer you get to the ground. 

One measurement of the atmosphere is its scale height. This is the distance one must climb before the air density (which closely matches air pressure*) decreases by a factor of e (2.718...), which means a decrease to 37%. When anything changes in value based on its amount, the number e always shows up just like pi shows up when circles are involved.

Scale height depends on things like the temperature, gravity, and gas molecule mass. So scale height can vary for different gasses in an atmosphere, but with the kind of mixing we have on Earth, the scale height of the different gases in our atmosphere is the same until you get above the stratosphere.

The scale height of our atmosphere is about five miles. Since the atmospheric density is decreasing by e for every scale height, all the air compressed to the surface and uniformly at standard atmospheric pressure is also five miles thick. So technically, the amount of scattering you observe looking hortizonally through five miles of air is the same amount you observing looking down from 200 miles up. 

So I guess we shouldn't be too surprised satellites can get clear images of the surface. Even though they more than 120 miles up, it only appears like they are looking through 5.1 miles of air at sea level air density. 

By the way, scale height also tells you how fast a balloon must expand in volume to remain buoyant. The scale height of Saturn's moon Titan is 30 miles. Keeping everything constant, a balloon should be able to climb about six times higher on Titan than Earth. Perhaps we should look at holding GPSL 2100 in Titan?

*I see there's about a 1% difference between air density and air pressure by the time a balloon climbs to 100,000 feet. By coincidence, Earth's gravity also decreases by 1% at 100,000 feet. Since pressure is related to force and force is due to gravity pulling on mass, I suspect that the difference between air density and air pressure is related to the decrease in gravity at 100,000 feet in altitude.

On Thu, Jun 11, 2020, 4:03 PM Joe WB9SBD <nss@...> wrote:
Watching the news this morning they had a thing on how they are using orbital satellites to monitor the Covid-19. It was amazing imagery!

I can understand Optics on getting the clear resolution. But how do they penetrate the blue haze?

The color balance was perfect in all the shots as if they were taken from a plane at 5000 feet say. Perfect crisp images and perfect color balance not a trace of Blue.

How?

Joe WB9SBD



Re: Imaging the Surface

Creager, Gerald J - Capt, CAP - Health Services Officer - (SWR-OK-001)
 

The big satellites use sensors on a bunch of discrete wavelengths, and the bandwidth of the sensors isn't too broad. They bring all the wavelengths down and post-process them into false-color images for almost everything released to the public, but there are some sensors that are "true color". These require significant pixel counts, but again, the image mechanism is different: Most are still line-scanners. Very fast line scanners. This allows them to keep the focus and parallax in control, and, their imagery is attitude stabilized, so they are always looking at the same angle, depending on mission.

Weather satellites are like this, although they might be looking with 20 different instruments at the same scene. The bandwidth is significant.

73
Gerry N5JXS



CAP E-Mail Logo

Capt Gerald J Creager, CAP
Health Services Officer - (SWR-OK-001)
(H) 979.229.5301
(C) 979.229.5301
U.S. Air Force Auxiliary
https://www.GoCivilAirPatrol.com/
https://www.okwgcap.org/
https://www.okwgcap.org/wingstaff




From: GPSL@groups.io <GPSL@groups.io> on behalf of Joe WB9SBD via groups.io <nss@...>
Sent: Thursday, June 11, 2020 21:42
To: GPSL@groups.io <GPSL@groups.io>
Subject: Re: [GPSL] Imaging the Surface
 
Thats what I was wondering how the Government from orbit has perfectly neutral colors.

Joe WB9SBD

On 6/11/2020 6:25 PM, L. Paul Verhage KD4STH wrote:
Yeah, I always see blue unless I shoot black and white near infrared.

On Thu, Jun 11, 2020, 5:02 PM Joe WB9SBD <nss@...> wrote:
I have yet to see a pic from say 60K and up from anyone's balloon, that you can say the image of the ground even when looking straight down is not color shifted way into the blue.

it's almost like a Black and white TV picture except it's Blue and white, everything is various shades of Blue.

Joe WB9SBD

On 6/11/2020 5:37 PM, L. Paul Verhage KD4STH wrote:
Interesting. I know near infrared penetrates the air like it wasn't there. But shorter wavelength light like blue is strongly scattered.

Perhaps because the satellite looks straight down, there's less air to scatter the light. When we look horizontally through the air, we are looking through miles of air at roughly the same density. When you look down, you are seeing throgh a column of air that increases the closer you get to the ground. 

One measurement of the atmosphere is its scale height. This is the distance one must climb before the air density (which closely matches air pressure*) decreases by a factor of e (2.718...), which means a decrease to 37%. When anything changes in value based on its amount, the number e always shows up just like pi shows up when circles are involved.

Scale height depends on things like the temperature, gravity, and gas molecule mass. So scale height can vary for different gasses in an atmosphere, but with the kind of mixing we have on Earth, the scale height of the different gases in our atmosphere is the same until you get above the stratosphere.

The scale height of our atmosphere is about five miles. Since the atmospheric density is decreasing by e for every scale height, all the air compressed to the surface and uniformly at standard atmospheric pressure is also five miles thick. So technically, the amount of scattering you observe looking hortizonally through five miles of air is the same amount you observing looking down from 200 miles up. 

So I guess we shouldn't be too surprised satellites can get clear images of the surface. Even though they more than 120 miles up, it only appears like they are looking through 5.1 miles of air at sea level air density. 

By the way, scale height also tells you how fast a balloon must expand in volume to remain buoyant. The scale height of Saturn's moon Titan is 30 miles. Keeping everything constant, a balloon should be able to climb about six times higher on Titan than Earth. Perhaps we should look at holding GPSL 2100 in Titan?

*I see there's about a 1% difference between air density and air pressure by the time a balloon climbs to 100,000 feet. By coincidence, Earth's gravity also decreases by 1% at 100,000 feet. Since pressure is related to force and force is due to gravity pulling on mass, I suspect that the difference between air density and air pressure is related to the decrease in gravity at 100,000 feet in altitude.

On Thu, Jun 11, 2020, 4:03 PM Joe WB9SBD <nss@...> wrote:
Watching the news this morning they had a thing on how they are using orbital satellites to monitor the Covid-19. It was amazing imagery!

I can understand Optics on getting the clear resolution. But how do they penetrate the blue haze?

The color balance was perfect in all the shots as if they were taken from a plane at 5000 feet say. Perfect crisp images and perfect color balance not a trace of Blue.

How?

Joe WB9SBD



Additional talks sought for GPSL 2020

Mark Conner N9XTN
 

GPSLers,

We still have room for additional talks for the Friday session!  I'd like to extend a particular invitation to those outside the US who might want to present something.  I know our UK friends in particular have had to be very creative with their RF solutions given their strict regulatory environment, and I'm sure many of us who are the "usual" GPSL attendees would like to hear how they overcame those limits (and stretched the state of the art in doing so).  I'm sure there are plenty of similar stories from elsewhere.

This is a great opportunity to see what other ARHAB communities are doing and cross-feed some ideas from around the world.

Our session will run from roughly 1400-2200 UTC on July 10 (exact timing will depend on number/duration of talks).  Please contact me at n9xtn@... if you are interested in presenting.  This is a collegial environment and don't be concerned if you're not a PowerPoint wizard or a Dale Carnegie speaker.  

73 de Mark N9XTN

Registration is now open for GPSL 2020

Zack Clobes W0ZC
 

As many of you already know, it's virtual this year. In order to receive your invite into the Zoom meeting, please register ASAP. See you all online!





Zack Clobes, W0ZC
Project: Traveler
www.projecttraveler.org

Join us on Facebook for the latest information:



Project: Traveler is a research project of Custom Digital Services, LLC. 

Re: Imaging the Surface

Hank Riley
 

Rayleigh scattering.    

Notice how the big cloudless areas of land as seen from far out in space (reference 1; looking "straight down") are not very blue tinted at all.  Conversely the balloon pictures from in or near the altitudes of the clouds, and including some look angles from the camera's point of view that are oblique and looking at the clouds, are remarkably bluish.
______________________________________________________________________




Re: Imaging the Surface

Joe WB9SBD
 

Thats what I was wondering how the Government from orbit has perfectly neutral colors.

Joe WB9SBD

On 6/11/2020 6:25 PM, L. Paul Verhage KD4STH wrote:
Yeah, I always see blue unless I shoot black and white near infrared.

On Thu, Jun 11, 2020, 5:02 PM Joe WB9SBD <nss@...> wrote:
I have yet to see a pic from say 60K and up from anyone's balloon, that you can say the image of the ground even when looking straight down is not color shifted way into the blue.

it's almost like a Black and white TV picture except it's Blue and white, everything is various shades of Blue.

Joe WB9SBD

On 6/11/2020 5:37 PM, L. Paul Verhage KD4STH wrote:
Interesting. I know near infrared penetrates the air like it wasn't there. But shorter wavelength light like blue is strongly scattered.

Perhaps because the satellite looks straight down, there's less air to scatter the light. When we look horizontally through the air, we are looking through miles of air at roughly the same density. When you look down, you are seeing throgh a column of air that increases the closer you get to the ground. 

One measurement of the atmosphere is its scale height. This is the distance one must climb before the air density (which closely matches air pressure*) decreases by a factor of e (2.718...), which means a decrease to 37%. When anything changes in value based on its amount, the number e always shows up just like pi shows up when circles are involved.

Scale height depends on things like the temperature, gravity, and gas molecule mass. So scale height can vary for different gasses in an atmosphere, but with the kind of mixing we have on Earth, the scale height of the different gases in our atmosphere is the same until you get above the stratosphere.

The scale height of our atmosphere is about five miles. Since the atmospheric density is decreasing by e for every scale height, all the air compressed to the surface and uniformly at standard atmospheric pressure is also five miles thick. So technically, the amount of scattering you observe looking hortizonally through five miles of air is the same amount you observing looking down from 200 miles up. 

So I guess we shouldn't be too surprised satellites can get clear images of the surface. Even though they more than 120 miles up, it only appears like they are looking through 5.1 miles of air at sea level air density. 

By the way, scale height also tells you how fast a balloon must expand in volume to remain buoyant. The scale height of Saturn's moon Titan is 30 miles. Keeping everything constant, a balloon should be able to climb about six times higher on Titan than Earth. Perhaps we should look at holding GPSL 2100 in Titan?

*I see there's about a 1% difference between air density and air pressure by the time a balloon climbs to 100,000 feet. By coincidence, Earth's gravity also decreases by 1% at 100,000 feet. Since pressure is related to force and force is due to gravity pulling on mass, I suspect that the difference between air density and air pressure is related to the decrease in gravity at 100,000 feet in altitude.

On Thu, Jun 11, 2020, 4:03 PM Joe WB9SBD <nss@...> wrote:
Watching the news this morning they had a thing on how they are using orbital satellites to monitor the Covid-19. It was amazing imagery!

I can understand Optics on getting the clear resolution. But how do they penetrate the blue haze?

The color balance was perfect in all the shots as if they were taken from a plane at 5000 feet say. Perfect crisp images and perfect color balance not a trace of Blue.

How?

Joe WB9SBD



Re: Imaging the Surface

L. Paul Verhage KD4STH
 

Yeah, I always see blue unless I shoot black and white near infrared.


On Thu, Jun 11, 2020, 5:02 PM Joe WB9SBD <nss@...> wrote:
I have yet to see a pic from say 60K and up from anyone's balloon, that you can say the image of the ground even when looking straight down is not color shifted way into the blue.

it's almost like a Black and white TV picture except it's Blue and white, everything is various shades of Blue.

Joe WB9SBD

On 6/11/2020 5:37 PM, L. Paul Verhage KD4STH wrote:
Interesting. I know near infrared penetrates the air like it wasn't there. But shorter wavelength light like blue is strongly scattered.

Perhaps because the satellite looks straight down, there's less air to scatter the light. When we look horizontally through the air, we are looking through miles of air at roughly the same density. When you look down, you are seeing throgh a column of air that increases the closer you get to the ground. 

One measurement of the atmosphere is its scale height. This is the distance one must climb before the air density (which closely matches air pressure*) decreases by a factor of e (2.718...), which means a decrease to 37%. When anything changes in value based on its amount, the number e always shows up just like pi shows up when circles are involved.

Scale height depends on things like the temperature, gravity, and gas molecule mass. So scale height can vary for different gasses in an atmosphere, but with the kind of mixing we have on Earth, the scale height of the different gases in our atmosphere is the same until you get above the stratosphere.

The scale height of our atmosphere is about five miles. Since the atmospheric density is decreasing by e for every scale height, all the air compressed to the surface and uniformly at standard atmospheric pressure is also five miles thick. So technically, the amount of scattering you observe looking hortizonally through five miles of air is the same amount you observing looking down from 200 miles up. 

So I guess we shouldn't be too surprised satellites can get clear images of the surface. Even though they more than 120 miles up, it only appears like they are looking through 5.1 miles of air at sea level air density. 

By the way, scale height also tells you how fast a balloon must expand in volume to remain buoyant. The scale height of Saturn's moon Titan is 30 miles. Keeping everything constant, a balloon should be able to climb about six times higher on Titan than Earth. Perhaps we should look at holding GPSL 2100 in Titan?

*I see there's about a 1% difference between air density and air pressure by the time a balloon climbs to 100,000 feet. By coincidence, Earth's gravity also decreases by 1% at 100,000 feet. Since pressure is related to force and force is due to gravity pulling on mass, I suspect that the difference between air density and air pressure is related to the decrease in gravity at 100,000 feet in altitude.

On Thu, Jun 11, 2020, 4:03 PM Joe WB9SBD <nss@...> wrote:
Watching the news this morning they had a thing on how they are using orbital satellites to monitor the Covid-19. It was amazing imagery!

I can understand Optics on getting the clear resolution. But how do they penetrate the blue haze?

The color balance was perfect in all the shots as if they were taken from a plane at 5000 feet say. Perfect crisp images and perfect color balance not a trace of Blue.

How?

Joe WB9SBD